DC ground fault circuit interrupter

Abstract

A ground fault circuit interrupter for a direct current (DC) system which can interrupt DC power connections to one or more loads when a fault is detected is disclosed herein. Specifically, the circuit interrupter includes a toroidal core having a winding wound around the core. An alternating current supply is coupled to the current sense winding. Source and return wires of an external DC current supply pass through the core, coupling the DC current supply to respective ends of an external DC load. A current imbalance between the source and return wires causes the core to saturate changing the impedance of the winding. The impedance change causes a fault signal to be generated and said fault signal is used to break the electrical connection between the external direct current supply and the external load.

Description

[0001] Under 35 U.S.C. 119(e), this application claims the benefit of the filing date of a provisional application having Ser. No. 60 / 648,860 which was filed on Jan. 28, 2005.FIELD OF THE INVENTION [0002] The present invention relates to a ground fault circuit interrupter, in general and to a direct current (DC) ground fault circuit interrupter, in particular. BACKGROUND OF THE INVENTION [0003] A ground fault circuit interrupter (GFCI) is a device that is capable of detecting abnormal current flow in an electrical system and, consequently, interrupt power to the electrical system in which the fault occurred. In such a manner the device can protect persons from electric shock and fire. In the absence of a ground fault, the GFCI can enable connection of power to the GFCI itself and to downstream electrical loads. When a ground fault is detected, the GFCI can open contacts to disconnect the power to the electrical loads. GFCIs are common in alternating current (AC) systems including th...

AI Technical Summary

Benefits of technology

[0015] Advantages of this design include but are not limited to a simple, economical ground fault circuit interrupter that can detect a ground fault without monitoring the frequency shift in the AC supply.

Problems solved by technology

When a ground fault is detected, a GFCI can interrupt both phase and neutral lines.

If there is a failure of insulation between the applied potential and ground with respect to any device, however, a ground current flow will result.

Similarly, if a failure of insulation occurs between the opposite polarity and ground, a short circuit across the full power supply could eventually evolve.

These devices, however, do not isolate the fault.

The sensing means and the means provided to determine the duty cycle of the voltage applied to the third winding, however, are complex and thereby not economical.

This approach merely detects a fault but does not disable the power supplied to the DC load from the DC source.

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